An estimated 5,430 men and women will be diagnosed with chronic myelogenous leukemia in 2012. Most people with chronic myelogenous leukemia have a genetic mutation, called the Philadelphia chromosome, which causes the bone marrow to make an enzyme called tyrosine kinase. This enzyme triggers the development of too many abnormal and unhealthy white blood cells called granulocytes. Granulocytes fight infection.

Bosulif is intended for patients with chronic, accelerated or blast phase Philadelphia chromosome positive chronic myelogenous leukemia who are resistant to or who cannot tolerate other therapies, including Imatinib. Bosulif works by blocking the signal of the tyrosine kinase that promotes the development of abnormal and unhealthy granulocytes.

The safety and effectiveness of Bosutinib was evaluated in a single clinical trial that enrolled 546 adult patients who had chronic, accelerated or blast phase chronic myelogenous leukemia. All patients had disease that progressed after treatment with Imatinib or Imatinib followed by Dasatinib and/or Nilotinib, or who could not tolerate the side effects of prior therapy. All patients in the trial were treated with Bosutinib.

In patients with chronic phase chronic myelogenous leukemia, efficacy was determined by the number of patients who experienced a major cytogenetic response ( McyR ) within the first 24 weeks of treatment. Results showed 34% of patients who had been previously treated with Imatinib achieved MCyR after 24 weeks. Of the patients who achieved MCyR at any time, 52.8% had their response last at least 18 months. Among patients previously treated with Imatinib followed by Dasatinib and/or Nilotinib, about 27% achieved MCyR within the first 24 weeks of treatment. Of those who achieved MCyR at any time, 51.4% had their MCyR last at least nine months.